Mysoline (primidone) is a barbiturate anticonvulsant, used to treat seizures when the patient does not respond well to other treatments. It can be used in all ages, but patients under 8 years old will require modified doses.

In use since the 1950s, Mysoline has since been largely overtaken by more modern anticonvulsants. However, it remains a viable choice when other medications do not produce a significant decrease in seizures or when patients are unable to take other medications, such as due to allergies or severe adverse effects.

Mysoline may be used on its own or with other medications to treat:

• Grand mal (tonic-clonic) seizures
• Psychomotor seizures
• Focal epileptic seizures
• Essential tremor

The medication has been used in a wide variety of other conditions, many unrelated to seizures, but hasn't produced significant benefit.

It has also been used to treat some psychiatric disorders with mixed results. Some found it tremendously helpful in treating depression and bipolar disorder, but in other cases it was found to increase aggression. Interestingly the medication is used in veterinary medicine to reduce aggression and promote calmness in some species. In humans these uses are off-label and patients interested in Mysoline to treat a psychiatric disorder should work with a doctor.

Taking Mysoline

Mysoline comes in tablets, usually taken 3 times per day but sometimes as often as 5 times per day. Food is optional, but may ease gastrointestinal side effects. For best results doses of Mysoline should be taken at the same times each day, to help keep levels of the drug consistent in the body.

Dosage is always individualized and always titrated up from low amounts. If switching from another medication to Mysoline, the old medication will likely be gradually reduced as Mysoline is gradually increased. Titration is important with Mysoline to help avert side effects.

In patients age 8 and up treatment is usually:

• Start with 100 to 125 mg once per day at bedtime for the first three days.
• Days four to six, take 100 to 125 mg twice per day; morning and bedtime.
• Days seven to nine, take 100 to 125 mg three times per day; morning, noon, and bedtime.
• Day 10 on, take 250 mg three times per day.
• 250 mg three times per day is sufficient for most patients.
• Do not exceed 2 g (500 mg four times per day) in a single day.

Patients age 7 and under:

• Administer 50 mg once per day at bedtime for the first three days.
• Days four to six, administer 50 mg twice per day; morning and bedtime.
• Days seven to nine, administer 100 mg twice per day; morning and bedtime.
• Day 10 on, administer 125 mg three times per day; morning, noon, and bedtime.

There's a good chance doctor instructions will deviate to some extent from the above, particularly with regard to the maintenance dose. Some individuals will respond just as well to lower doses, others respond well to higher doses but experience adverse effects, while still others will need a higher maintenance dose for significant benefit.

Likewise some patients have much better results when doses are taken more spread out through the day; instead of dividing total daily dosage into three smaller doses, a doctor may advise dividing total daily dosage into four or five smaller doses.

Treatment can continue for as long as it provides benefit. If treatment ends---including switching to another medication---Mysoline should be gradually reduced over time. Abruptly ending treatment can cause unpleasant withdrawal effects, including anxiety and hallucinations. A doctor can help develop a discontinuation plan, which will likely resemble a reverse of the instructions above.

Precautions & Side Effects

Patients with any other major medical condition should be sure to make the prescribing doctor aware. Mysoline will most likely still be an option, but dosage adjustments may be necessary.

This product can cause severe birth defects in unborn babies, as Mysoline can lower folic acid levels. However, seizures are also dangerous to unborn babies as well as mothers. Speak with a doctor if pregnancy is discovered while taking Mysoline.

Note that this product interferes with all hormonal birth control, be it pills, patches, or injections. Alternate forms of birth control should be considered.

Mysoline lowers vitamin K levels, which can make it difficult for blood to coagulate. If unexplained or excessive bleeding is noticed, speak with a doctor. Patients taking blood thinners or who have clotting issues may not be good candidates for this medication.

Drowsiness and dizziness are common side effects of Mysoline. Use caution when performing dangerous tasks until effects are known. Other sedatives, including alcohol or marijuana, can worsen this effect.

Most common side effects are mild and transient, meaning they stop occurring as the body adjusts to treatment. Common side effects include:

• Headache
• Dizziness
• Drowsiness
• Mild fatigue
• Appetite loss
• Nausea
• Vomiting

Rarely serious side effects develop. Seek medical attention if experiencing:

• Clumsiness
• Vision changes
• Unexplained bruising or bleeding
• Severe fatigue
• Weakness
• Slow heart rate
• Fast or shallow breathing
• Fainting

Numerous other medications can interact with Mysoline, including those of the over-the-counter variety. Most of these interactions don't produce complications of immediate concern, but can reduce Mysoline's effectiveness over time. Always double-check with a doctor or pharmacist before mixing medications, including seemingly-innocuous over-the-counter treatments.